A driver of moving vehicles, including cars, trains, planes and ships, sometimes feels drowsy during the drive. This drowsiness decreases attentiveness of the driver, leading to various accidents. To prevent this kind of drowsiness and its consecutive decrease of attentiveness, various methods have been developed. One of the most common methods is letting the driver inhale gas or liquid containing awakening substance, for it is expected to intercept driving maneuver less.
One of the typical methods to let the driver inhale awakening gas or such liquid is to place an aroma diffuser of which aroma contains incense and caffeine, which has direct-awakening substance, to let it evaporate. This provides an awakening environment or a preventive environment of drowsiness (Patent literature 1).